1. Field of the Invention
The present invention relates to a pixel structure, and particularly to a pixel structure for a transflective thin film transistor (TFT) liquid crystal display (LCD) for improving efficiency in backlight utilization.
2. Description of Related Art
Since the first cathode ray tube (CRT) television was invented, display technology has developed rapidly. However, CRT displays have obvious disadvantages such as large size, heavy weight, high radiation and poor pixel quality, and therefore various flat display panels are explored and introduced. Among them, LCDs, with advantages such as compact size, power consumption, no radiation, full color display, and portability, have become the most developed and popular products. LCDs are used in various applications including cellular phone, electronic dictionary, digital camera, digital camcorder, personal digital assistant, notebook computer and desktop computer.
TFT LCDs can be generally categorized into transmissive type, reflective type and transflective type, according to the light source and array substrates used. A typical transmissive TFT LCD uses a backlight source, and employs transparent electrodes as pixel electrodes of the TFT array substrate for allowing backlights to transmit through. A typical reflective TFT LCD uses a front-light source and/or ambient lights as a light source, and employs metal or other reflective material as reflective electrodes for reflecting the front-lights or the ambient lights. A typical transflective TFT LCD can be viewed as a combination of a transmissive TFT LCD and a reflective TFT LCD, taking advantages of the backlight source and the front-light source or the ambient lights for display.
In the conventional transflective TFT LCDs, the reflective layers are usually designed to have rough surfaces for obtaining widely distributed reflected lights. However, the process to make the surfaces rough increases production costs. Further, when the backlight source provides backlights for display, only those radiating on the transparent electrodes rather than those radiating on the reflective layer can be used. Therefore, such a conventional transflective TFT LCD has lower utilization efficiency of lights provided by the backlight module.